1. Field of the Invention
The present invention generally relates to a control integrated circuit (control IC) used for floppy disk drives (FDD), and more particularly to an FDD control IC which can be used for driving both a stepper motor used in a one-inch-thick FDD and a stepper motor used in a half-inch-thick FDD.
2. Description of the Related Art
Generally, in one-inch-thick FDDs used in desk-top personal computers, a large stepper motor (hereinafter referred to as a xe2x80x9cone-inch stepper motorxe2x80x9d) is used for moving a head to a predetermined position of a floppy disk because of the comparatively large space inside the casing of the personal computer. In contrast, in half-inch-thick FDDs used in notebook-type personal computers, a small stepper motor (hereinafter referred to as a xe2x80x9chalf-inch stepper motorxe2x80x9d) is used because of the comparatively small space inside the casing of the personal computer.
The stepper motors used in the FDDs are driven by a control IC, which is mounted on a circuit board provided within the casing of the personal computer. Generally, the saturation voltage Vsat of the one-inch stepper motor is different from that of the half-inch stepper motor. Additionally, the number of signals for an interface required for driving the half-inch stepper motor is slightly greater than that of the one-inch stepper motor. Accordingly, a greater number of pins should be disposed on the circuit board. More specifically, the number of pins provided on the circuit board for driving the one-inch stepper motor is 44, while the number of pins for driving the half-inch stepper motor is 48. Thus, because of the difference in the number of pins, the number of pads provided for a control IC for driving the one-inch stepper motor is different from the number of pads for driving the half-inch stepper motor. More specifically, 44 pads are required for a control IC for driving the one-inch stepper motor, while 48 pads are required for a control IC for driving the half-inch stepper motor.
Because of recent remarkable progress in manufacturing techniques, ICs can now be mass produced. Accordingly, the manufacturing cost has become less expensive as has the unit price of the ICs. This is also true for control ICs used in FDDs.
As discussed above, however, different FDD control ICs are used for driving the one-inch stepper motor and the half-inch stepper motor. Accordingly, different manufacturing methods are required for manufacturing the FDD control ICs. Additionally, the production volume for each type of control ICs is limited, thereby increasing the manufacturing cost on the whole.
In order to solve the above-described problems, the same control IC may be used for driving the one-inch stepper motor and the half-inch stepper motor. However, the seek pattern having a timing for driving the one-inch stepper motor is different from the seek pattern having a timing used for driving the half-inch stepper motor. Thus, it is difficult to obtain a control IC which can be used for driving both the one-inch stepper motor and the half-inch stepper motor so that they can be properly operated.
Accordingly, in view of the above-described technical background, it is an object of the present invention to provide an FDD control IC which can be used for driving both a one-inch stepper motor and a half-inch stepper motor.
It is another object of the present invention to provide an FDD control IC for driving a one-inch stepper motor and a half-inch stepper motor so that they can be properly operated.
In order to achieve the above objects, according to the present invention, there is provided a control IC mounted on a circuit board, for driving both a one-inch stepper motor used in a FDD and a half-inch stepper motor used in a FDD. The control IC includes at least a number of pads required for driving the half-inch stepper motor. When the control IC drives the one-inch stepper motor or the half-inch stepper motor, the saturation voltage, the arrangement of the pads having the same functions for driving the one-inch stepper motor and the half-inch stepper motor, read/write constants for reading and writing from and into a floppy disk are set to be equal for both the one-inch stepper motor and the half-inch stepper motor.
With this configuration, the one-inch stepper motor and the half-inch stepper motor can be driven in a suitable state. Since the same control IC is used for both types of stepper motors, the production volume of the control ICs can be increased, and the manufacturing cost can also be decreased.
In the aforementioned control IC, the pads may include a detection pad for receiving an intermediate voltage between a power supply voltage and a reference voltage. The detection pad may not be electrically connected to any pin disposed on the circuit board when the control IC is used for driving the one-inch stepper motor, and the detection pad may be electrically connected to a detection pin which is disposed on the circuit board and which is selectively maintained at the power supply voltage or the reference voltage when the control IC is used for driving the half-inch stepper motor.
In this case, the control IC may generate a seek pattern having a timing suitable for the one-inch stepper motor when the voltage of the detection pad is the intermediate voltage, and the control IC may generate a seek pattern having a timing suitable for the half-inch stepper motor when the voltage of the detection pad is the power supply voltage or the reference voltage.
With this arrangement, by detecting the voltage of the detection pad, the control IC is able to instantly determine which type of stepper motor, i.e., the one-inch stepper motor or the half-inch stepper motor, the control IC is driving. Thus, the control IC can generate a seek pattern having a timing suitable for the detected type of stepper motor. As a result, the one-inch stepper motor and the half-inch stepper motor can be driven in a more suitable state.